Far end crosstalk compensation

ABSTRACT

Methods and systems for providing crosstalk compensation in a jack are disclosed. According to one method, the crosstalk compensation is adapted to compensate for undesired crosstalk generated at a capacitive coupling located at a plug inserted within the jack. The method includes positioning a first capacitive coupling a first time delay away from the capacitive coupling of the plug, the first capacitive coupling having a greater magnitude and an opposite polarity as compared to the capacitive coupling of the plug. The method also includes positioning a second capacitive coupling at a second time delay from the first capacitive coupling, the second time delay corresponding to an average time delay that optimizes near end crosstalk. The second capacitive coupling has generally the same overall magnitude but an opposite polarity as compared to the first capacitive coupling, and includes two capacitive elements spaced at different time delays from the first capacitive coupling.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/028,040, filed Feb. 12, 2008, which applicationis hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates generally to telecommunications equipment.More particularly, the present invention relates to telecommunicationsjacks that are configured to compensate for near end crosstalk and farend crosstalk.

BACKGROUND

In the field of data communications, communications networks typicallyutilize techniques designed to maintain or improve the integrity ofsignals being transmitted via the network (“transmission signals”). Toprotect signal integrity, the communications networks should, at aminimum, satisfy compliance standards that are established by standardscommittees, such as the Institute of Electrical and ElectronicsEngineers (IEEE). The compliance standards help network designersprovide communications networks that achieve at least minimum levels ofsignal integrity as well as some standard of compatibility.

One prevalent type of communication system uses twisted pairs of wiresto transmit signals. In twisted pair systems, information such as video,audio and data are transmitted in the form of balanced signals over apair of wires. The transmitted signal is defined by the voltagedifference between the wires.

Crosstalk can negatively affect signal integrity in twisted pairsystems. Crosstalk is unbalanced noise caused by capacitive and/orinductive coupling between wires and a twisted pair system. Crosstalkcan exist in many variants, including near end crosstalk, far endcrosstalk, and alien crosstalk. Near end crosstalk refers to crosstalkdetected at the same end of a wire pair as the inductance causing it,while far end crosstalk refers to crosstalk resulting from inductance ata far end of a wire pair. Alien crosstalk refers to crosstalk thatoccurs between different cables (i.e. different channels) in a bundle,rather than between individual wires or circuits within a single cable.Alien crosstalk can be introduced, for example, at a multiple connectorinterface. With increasing data transmission speeds, increasing aliencrosstalk is generated among cables, and must be accounted for indesigning systems in which compensation for the crosstalk is applied.The effects of all crosstalk become more difficult to address withincreased signal frequency ranges.

The effects of crosstalk also increase when transmission signals arepositioned closer to one another. Consequently, communications networksinclude areas that are especially susceptible to crosstalk because ofthe proximity of the transmission signals. In particular, communicationsnetworks include connectors that bring transmission signals in closeproximity to one another. For example, the contacts of traditionalconnectors (e.g., jacks and plugs) used to provide interconnections intwisted pair telecommunications systems are particularly susceptible tocrosstalk interference. Furthermore, alien crosstalk has been observedthat could not be explained by the current models which sum connectorsand cable component results to calculate channel results. This “excess”alien crosstalk is not compensated for in existing designs.

FIG. 1 shows a prior art panel 20 adapted for use with a twisted pairtelecommunications system. The panel 20 includes a plurality of jacks 22placed in close proximity with one another. Each jack 22 includes a port24 adapted to receive a standard telecommunications plug 26. Each of thejacks 22 is adapted to be terminated to four twisted pairs oftransmission wires. As shown at FIG. 2, each of the jacks 22 includeseight contact springs labeled as having positions 1-8. In use, contactsprings 4 and 5 are connected to a first pair of wires, the contactsprings 1 and 2 are connected to a second pair of wires, contact springs3 and 6 are connected to a third pair of wires, and contact springs 7and 8 are connected to a fourth pair of wires. As shown at FIG. 3, atypical plug 26 also has eight contacts (labeled 1-8) adapted tointerconnect with the corresponding eight contacts of the jack 22 whenthe plug is inserted within the port 24.

To promote circuit density, the contacts of the jacks and the plugs arerequired to be positioned in fairly close proximity to one another.Thus, the contact regions of the jacks and plugs are particularlysusceptible to crosstalk. Furthermore, certain pairs of contacts aremore susceptible to crosstalk than others. For example, the first andthird pairs of contacts in the plugs and jacks are typically mostsusceptible to crosstalk.

To address the problems of crosstalk, jacks have been designed withcontact spring configurations adapted to reduce the capacitive couplinggenerated between the contact springs so that crosstalk is minimized. Analternative approach involves intentionally generating crosstalk havinga magnitude and phase designed to compensate for or correct crosstalkcaused at the plug or jack. Typically, crosstalk compensation can beprovided by manipulating the positioning of the contacts or leads of thejack or can be provided on a circuit board used to electrically connectthe contact springs of the jack to insulation displacement connectors ofthe jack.

The telecommunications industry is constantly striving toward largersignal frequency ranges. As transmission frequency ranges widen,crosstalk becomes more problematic. Thus, there is a need for furtherdevelopment relating to crosstalk remediation.

SUMMARY

In accordance with the present disclosure, the above and other problemsare solved by the following.

In a first aspect, a method for providing crosstalk compensation in ajack is disclosed. According to the method, the crosstalk compensationis adapted to compensate for undesired crosstalk generated at acapacitive coupling located at a plug inserted within the jack. Themethod includes positioning a first capacitive coupling a first timedelay away from the capacitive coupling of the plug, the firstcapacitive coupling having a greater magnitude and an opposite polarityas compared to the capacitive coupling of the plug. The method alsoincludes positioning a second capacitive coupling at a second time delayfrom the first capacitive coupling, the second time delay correspondingto an average time delay that optimizes near end crosstalk. The secondcapacitive coupling has generally the same overall magnitude but anopposite polarity as compared to the first capacitive coupling, andincludes two capacitive elements spaced at different time delays fromthe first capacitive coupling.

In a second aspect, a telecommunications jack is disclosed for use in atwisted pair system. The jack includes a housing defining a port forreceiving a plug. The jack also includes a plurality of contact springsadapted to make electrical contact with the plug when the plug isinserted into the port of the housing. The jack includes a plurality ofwire termination contacts for terminating wires to the jack, and acircuit board including conductive tracks that electrically connect thecontact springs to the wire termination contacts. The jack furtherincludes a crosstalk compensation arrangement that provides crosstalkcompensation between selected tracks of the circuit board. The crosstalkcompensation arrangement includes a first zone of compensation a firsttime delay away from the capacitive coupling of the plug and a secondzone of compensation at an second time delay from the first zone ofcompensation, the second zone of compensation including two capacitiveelements spaced at different time delays from the first zone ofcompensation to optimize far end crosstalk and having an average timedelay that optimizes near end crosstalk.

In a third aspect, a crosstalk compensation system within atelecommunications jack is disclosed. The crosstalk compensation systemincludes a circuit board and a plurality of contact springs mounted onthe circuit board, the contact springs including first, second, third,fourth, fifth, sixth, seventh and eighth consecutively arranged contactsprings. The crosstalk compensation system further includes a pluralityof wire termination contacts mounted on the circuit board, the wiretermination contents including first, second, third, fourth, fifth,sixth, seventh and eighth wire termination contacts for terminatingwires to the jack, and a plurality of tracks on the circuit board, thetracks including first, second, third, fourth, fifth, sixth, seventh andeighth tracks that respectively electrically connect the first, second,third, fourth, fifth, sixth, seventh and eighth contact springs to thefirst, second, third, fourth, fifth, sixth, seventh and eighth wiretermination contacts. The crosstalk compensation system includes acrosstalk compensation arrangement that provides crosstalk compensationbetween the tracks of the circuit board. The crosstalk compensationarrangement includes a first zone of compensation a first time delayaway from the contact springs and a second zone of compensation at ansecond time delay from the first zone of compensation, the second zoneof compensation including two capacitive elements spaced at differenttime delays from the first capacitive coupling and having an averagetime delay that that optimizes near end crosstalk.

In a fourth aspect, a method for determining the positions of first andsecond zones of crosstalk compensation in a jack is disclosed. Themethod is directed to a jack in which the first and second zones ofcrosstalk compensation are adapted to compensate for undesired crosstalkcaused by an undesired capacitive coupling located at a plug insertedwithin the jack, the first zone of crosstalk compensation including afirst capacitive coupling positioned a first time delay away from theundesired capacitive coupling of the plug, the first capacitive couplinghaving a greater magnitude and an opposite polarity as compared to theundesired capacitive coupling of the plug, the second zone of crosstalkcompensation including a second capacitive coupling having twocapacitive elements positioned, on average, a second time delay awayfrom the first capacitive coupling, the second capacitive couplinghaving generally the same magnitude but an opposite polarity as comparedto the first capacitive coupling. The method includes positioning thefirst and second capacitive couplings in initial positions in which thefirst and second time delays are generally equal to one another. Themethod also includes adjusting the position of the second capacitivecoupling from the initial position to an adjusted position to provideimproved near end crosstalk compensation. The method further includesadjusting the position of the first and second capacitive elements todifferent lengths to provide improved far end crosstalk compensationwhile maintaining the adjusted position of the second capacitivecoupling as the average position of the first and second capacitiveelements.

In a fifth aspect, a method of designing a crosstalk compensation systemfor a telecommunications jack is disclosed. The method includespositioning a first zone of crosstalk compensation across at least afirst wire pair and a second wire pair on a circuit board within atelecommunications jack, the first zone of crosstalk compensation placedat a first distance from contact springs associated with the first wirepair and the second wire pair. The method also includes positioning asecond zone of crosstalk compensation across the at least first andsecond wire pairs at a second distance from the first zone of crosstalkcompensation, the second zone of crosstalk compensation including afirst capacitive coupling and a second capacitive coupling. The methodfurther includes altering the position of the capacitive couplings toestablish a distance between the first capacitive coupling and thesecond capacitive coupling while maintaining the second distance as anaverage distance from the first zone of crosstalk compensation. Usingthe method disclosed, altering the position of the capacitive couplingsprovides improved far end crosstalk compensation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a prior art telecommunications panel;

FIG. 2 is a schematic illustration of a prior art jack;

FIG. 3 is a schematic representation of a prior art telecommunicationsplug;

FIG. 4 is a front, perspective view of a telecommunications jack havingfeatures that are examples of inventive aspects in accordance with theprinciples of the present disclosure;

FIG. 5 is an exploded view of the jack of FIG. 4;

FIG. 6 is a side view of the circuit board, insulation displacementconnectors and contact springs of the telecommunications jack of FIG. 4;

FIG. 7 is a front view of the circuit board, contact springs andinsulation displacement connectors of FIG. 6;

FIG. 8 is a top view of the circuit board and contact springs of FIG. 6;

FIG. 9 is a cross-sectional view taken along section line 9-9 of FIG. 8;

FIG. 10 is a schematic diagram showing a crosstalk compensation schemeincorporated into the telecommunications jack of FIG. 4;

FIG. 11 is a schematic diagram showing a compensation arrangement usedto provide crosstalk compensation between the 4-5 and 3-6 pairs of thetelecommunications jack of FIG. 4;

FIG. 12 is a schematic vector diagram showing a compensation arrangementused to provide crosstalk compensation between the 4-5 and 7-8 pairs ofthe telecommunications jack of FIG. 4;

FIG. 13 is a tracing overlay view of the circuit board used in thetelecommunications jack of FIG. 4;

FIG. 14 shows a front conductive layer of the circuit board used in thetelecommunications jack of FIG. 4;

FIG. 15 shows a middle conductive layer of the circuit board used in thetelecommunications jack of FIG. 4; and

FIG. 16 is shows a back conductive layer of the circuit board used inthe telecommunications jack of FIG. 4.

DETAILED DESCRIPTION

Various embodiments of the present disclosure will be described indetail with reference to the drawings, wherein like reference numeralsrepresent like parts and assemblies throughout the several views.Additionally, any examples set forth in this specification are notintended to be limiting and merely set forth some of the many possibleembodiments for how aspects of the disclosure may be practiced.

In general, the present disclosure relates to methods and systems forimproving far end crosstalk compensation without adversely affectingnear end crosstalk compensation within a telecommunications jack. Thepresent disclosure generally describes crosstalk compensation schemes inwhich near end and far end crosstalk are accounted for and compensatedagainst. In certain aspects, the crosstalk compensation is achieved byuse of at least two stages of capacitive compensation, in which thesecond stage is placed at an average time delay from the first stagesuch that near end crosstalk is optimized. The second stage has at leasttwo capacitive elements spaced at different time delays from the firstcapacitive coupling to optimize far end crosstalk.

The present disclosure also relates to methods and systems forcompensating for alien crosstalk in a telecommunications jack. Thepresent disclosure describes crosstalk compensation schemes in whichalien crosstalk is compensated against, such as by selecting imbalancedcapacitive arrangements across wire pairs to reduce the overallcrosstalk experienced in a system, despite the potential for imbalancedcompensation between wire pairs within a single jack.

FIGS. 4 and 5 show a telecommunications jack 120 (i.e., atelecommunications connector) having features that are examples ofinventive aspects in accordance with the principles of the presentdisclosure. The jack 120 includes a dielectric housing 122 having afront piece 124 and a rear piece 126. The front and rear pieces 124, 126can be interconnected by a snap fit connection. The front piece 124defines a front port 128 sized and shaped to receive a conventionaltelecommunications plug (e.g., an RJ style plug such as an RJ 45 plug).The rear piece 126 defines an insulation displacement connectorinterface and includes a plurality of towers 130 adapted to houseinsulation displacement connector blades/contacts. The jack 120 furtherincludes a circuit board 132 that mounts between the front and rearpieces 124, 126 of the housing 122. A plurality of contact springsCS₁-CS₈ are terminated to a front side of the circuit board 132. Aplurality of insulation displacement connector blades IDC₁-IDC₈ areterminated to a back side of the circuit board 132. The contact springsCS₁-CS₈ extend into the front port 128 and are adapted to beelectrically connected to corresponding contacts provided on a plug whenthe plug is inserted into the front port 128. The insulationdisplacement connector blades IDC₁-IDC₈ fit within the towers 130 of therear piece 126 of the housing 122. The circuit board 132 has tracksT₁-T₈ (e.g., tracings, see FIGS. 14-17) that respectively electricallyconnect the contact springs CS₁-CS₈ to the insulation displacementconnector blades IDC₁-IDC₈.

In use, wires are electrically connected to the contact springs CS₁-CS₈by inserting the wires between pairs of the insulation displacementconnector blades IDC₁-IDC₈. When the wires are inserted between pairs ofthe insulation displacement connector blades IDC₁-IDC₈, the blades cutthrough the insulation of the wires and make electrical contact with thecenter conductors of the wires. In this way, the insulation displacementconnector blades IDC₁-IDC₈, which are electrically connected to thecontact springs CS₁-CS₈ by the tracks on the circuit board, provide anefficient means for electrically connecting a twisted pair of wires tothe contact springs CS₁-CS₈ of the jack 120.

The contact springs CS₁-CS₈ are shown more clearly in FIGS. 6-8. Therelative positioning, shape and curvature of the contact springs CS₁-CS₈is preferably adapted to provide some initial crosstalk compensation atthe jack 120.

The circuit board 132 of the jack 120 is preferably a multiple layercircuit board. For example, FIG. 9 shows the circuit board 132 includinga first conductive layer 140, a second conductive layer 142 and a thirdconductive layer 144. The first and second conductive layers 140, 142are separated by a first dielectric layer 146. The second and thirdconductive layers 142, 144 are separated by a second dielectric layer148. The first conductive layer 140 is located at a front side of thecircuit board 132 and the third conductive layer 144 is located at aback side of the circuit board 132. The contact springs CS₁-CS₈ aremounted at the front side of the circuit board 132, while the insulationdisplacement connector blades IDC₁-IDC₈ are mounted at the back side ofthe circuit board 132. Vias extend through the first and seconddielectric layers 146, 148 to provide electrical connections between theconductive layers 140, 142 and 144. The conductive layers 140, 142 and144 are defined by electrically the conductive tracks T₁-T₈ (see FIGS.14-17). The tracks T₁-T₈ are formed (e.g., etched or otherwise provided)on the dielectric layers 146, 148.

The circuit board 132 preferably includes structures for compensatingfor near end crosstalk that occurs at the jack/plug interface. Incertain embodiments, the structures for compensating for near endcrosstalk include capacitive couplings provided between the first andsecond conductive layers 140, 142. In preferred embodiments, thecapacitive couplings are provided by sets of opposing, generallyparallel capacitive plates located at the first and second conductivelayers 140, 142. To increase the magnitude of the capacitive couplingprovided between the capacitive plates of the first and secondconductive layers 140, 142, it is desirable for the first dielectriclayer 146 to be relatively thin. For example, in certain embodiments thefirst dielectric layer 146 can have a thickness t₁ less than about 0.01inches, or less than about 0.0075 inches, or less than about 0.005inches, or less than 0.003 inches. In other embodiments, the thicknesst₁ can be in the range of 0.001 inches to 0.003 inches or in the rangeof 0.001 inches to 0.005 inches. In a preferred embodiment, thethickness t₁ is about 0.002 inches.

In certain embodiments, the first dielectric layer 146 can be made of amaterial having a relatively low dielectric constant. As used herein,dielectric constants are dielectric constants relative to air. Incertain embodiments, the dielectric constant of the first dielectriclayer 146 can be equal to or less than about 5. In other embodiments,the dielectric constant of the first dielectric layer 146 can be lessthan or equal to about 4 or less than or equal to about 3. An examplematerial for manufacturing the first dielectric layer 146 is a flameresistant 4 (FR-4) circuit board material. FR-4 circuit board materialis a composite of a resin epoxy reinforced with a woven fiberglass mat.

The second dielectric layer 148 is preferably configured to isolate thethird conductive layer 144 from the first and second conductive layers140, 142. The second dielectric layer 148 can have a different thicknesst₂ than the thickness t₁ of the first dielectric layer 146. In certainembodiments, the second dielectric layer 148 is at least 2.5 timesthicker than the first dielectric layer 146 or at least five timesthicker than the first dielectric layer 146. In still other embodiments,the second dielectric layer 148 is at least 10 times or at least 20times thicker than the first dielectric layer 146. In one exampleembodiment, the thickness t₂ of the second dielectric layer 148 is inthe range of 0.050 inches to 0.055 inches. In another exampleembodiment, the thickness t₂ of the second dielectric layer 148 is inthe range of 0.040 inches to 0.050 inches.

The second dielectric layer 148 can also be manufactured of a differentmaterial as compared to the first dielectric layer 146. In certainembodiments, the second dielectric layer can have different dielectricproperties as compared to the first dielectric layer 146. For example,in certain embodiments the first dielectric layer 146 can have adielectric constant that is greater (e.g., at least 1.5 times or atleast 2 times greater) than the dielectric constant of the seconddielectric layer 148. In one example, the second dielectric layer 148can be manufactured of a material such as FR-4. Of course, it will beappreciated that other materials could also be used.

The circuit board 132 includes a number of capacitive couplings havingmagnitudes and locations adapted to compensate for near end crosstalkand far end crosstalk. These forms of crosstalk are particularlyproblematic between the 4-5 and 3-6 pairs. To compensate for near endcrosstalk between the 4-5 and 3-6 pairs, three interdependent zones ofcompensation are used between tracks T₄₋₅ and tracks T₃₋₆. As shown atFIG. 10, the three interdependent zones of compensation include a firstzone of compensation Z_(A1), a second zone of compensation Z_(A2) and athird zone of compensation Z_(A3). The first zone of compensation Z_(A1)includes a capacitive coupling C1 between track T₃ and track T₅, and acapacitive coupling C2 between track T₄ and track T₆. The second zone ofcompensation Z_(A2) includes a capacitive coupling C3 between track T₃and track T₄, and a capacitive coupling C4 between track T₅ and trackT₆. The third zone of compensation Z includes a capacitive coupling C5between track T₃ and track T₅, and a capacitive coupling C6 betweentrack T₄ and track T₆.

To compensate for far end crosstalk, the capacitive couplings C3 and C4are spaced apart, such that the average distance between the zones ofcompensation is as described below in FIG. 11, but the distances for theC3 and C4 couplings differ. As shown, coupling C3 is placed closer tothe first zone of compensation Z_(A1) than coupling C4 while maintainingthe average position of the zone Z_(A2) such that the distance betweenzones is as described below in FIG. 11.

In the embodiments shown in the present disclosure, the capacitivecouplings C1 and C2 are equal in magnitude and location, maintainingsymmetry across the pairs. However, in certain embodiments, capacitivecouplings C1 and C2 may be selected such that they differ in magnitudeto compensate for alien crosstalk including the “excess” crosstalkpreviously mentioned, which is noted to be worst in the case of the 3-6pair. Specifically, it was determined that changes to alien crosstalkcan be made, both positively and negatively, by purposefully modifyingthe size of the compensating capacitors, causing them to becomeasymmetric in size and coupling. For example, in certain embodiments,the magnitude of capacitor C1 is greater than the magnitude of capacitorC2, which can reduce the alien crosstalk generated at the 3-6 pair. Itis observed that, analogously to varying the magnitudes of C1 and C2,varying the relative magnitudes of the capacitive couplings within azone of compensation in the compensation between the 4-5 and 3-6 pairscan improve the alien crosstalk observed. This is understood to have theeffect of compensating for the overall plug and jack configuration, asopposed to typical crosstalk compensation schemes which generally onlyaccount for crosstalk generated in the jack. Additional detailsregarding methods and configurations for compensating for aliencrosstalk are described below.

To address overall crosstalk between the 4-5 and 3-6 pairs, a relativelylarge amount of capacitance is used. This large amount of capacitancecan cause the jack to have unacceptable levels of return loss. Methodsfor addressing this return loss are addressed in U.S. patent applicationSer. No. 11/402,544, filed Apr. 11, 2006 and entitled“TELECOMMUNICATIONS JACK WITH CROSSTALK MULTI-ZONE CROSSTALKCOMPENSATION AND METHOD FOR DESIGNING”, which is hereby incorporated byreference in its entirety.

FIG. 11 is a schematic diagram representative of the compensationarrangement used to provide crosstalk compensation between the 4-5 and3-6 pairs. As shown at FIG. 11, the compensation arrangement includes afirst vector 100, a second vector 102, a third vector 104, and a fourthvector 106. The first vector 100 and the third vector 104 have positivepolarities, while the second vector 102 and the fourth vector 106 havenegative polarities. The first vector 100 has a magnitude of M andcorresponds to crosstalk introduced at the plug. The second vector 102has a magnitude of about −3M and corresponds to the overall crosstalkintroduced at the first zone of crosstalk Z_(A1) generated by the boardand springs. The third vector 104 has a magnitude of about 3M andcorresponds to the overall crosstalk introduced at the second zone ofcompensation Z_(A2). The fourth vector 106 has a magnitude of about −Mand corresponds to the overall crosstalk introduced at the third zone ofcompensation Z_(A3). It will be appreciated that each vector is a lumpsum of the total crosstalk or crosstalk compensation provided at eachrespective compensation zone, with the vectors being placed at thecenters or midpoints of the compensation zones.

In designing the compensation scheme of FIG. 11, a number of factors aretaken into consideration when determining the placement of thecompensation zones. One factor includes the need to accommodate signaltravel in both directions (i.e., in forward and reverse directions)through the tracks on the circuit board. To accommodate forward andreverse transmissions through the circuit board, the compensation schemepreferably has a configuration with forward and reverse symmetry. It isalso desirable for the compensation scheme to provide optimizedcompensation over a relatively wide range of transmission frequencies.For example, in one embodiment, performance is optimized for frequenciesranging from 1 MHz to 500 MHz. It is further desirable for thecompensation arrangement to take into consideration the phase shiftsthat occur as a result of the time delays that take place as signalstravel between the zones of compensation.

To minimize the effect of phase shift in the compensation arrangement,it is preferred for the second vector 102 to be positioned as close aspossible to the first vector 100. In FIG. 11, the time delay between thefirst vector 100 and the second vector 102 is shown as x. In one exampleembodiment, x can be about 100 picoseconds for a signal having atransmission speed of 3×10⁸ meters per second.

To maintain forward and reverse symmetry, it is preferred for the timedelay between the third vector 104 and the fourth vector 106 to beapproximately the same as the time delay between the first vector 100and the second vector 102. As shown in FIG. 11, the time delay betweenthe third and fourth vectors is depicted as x.

The time delay y between the second vector 102 and the third vector 104is preferably selected to optimize the overall compensation effect ofthe compensation scheme over a relatively wide range of frequencies. Byvarying the time delay y between the second vector 102 and the thirdvector 104, the phase angles of the first and second compensation zonesare varied thereby altering the amount of compensation provided atdifferent frequencies. In one example embodiment, to design the timedelay y, the time delay y is initially set with a value generally equalto x (i.e., the time delay between the first vector 102 and the secondvector 104). The system is then tested or simulated to determine if anacceptable level of compensation is provided across the entire signalfrequency range intended to be used. If the system meets the near endcrosstalk requirements with the value y set equal to x, then no furtheradjustment of the value y is needed. If the compensation scheme failsthe near end crosstalk requirements at higher frequencies, the timedelay y can be shortened to improve performance at higher frequencies.If the compensation scheme fails the near end crosstalk requirements atlower frequencies, the time delay y can be increased to improvecrosstalk performance for lower frequencies. It will be appreciated thatthe time delay y can be varied without altering forward and reversesymmetry.

It has been determined that when magnitudes of the second and thirdvectors 102, 104 are respectively about −3M and about 3M, the distance yis preferably greater than the distance x to provide optimized crosstalkcompensation. However, if the magnitudes of the vectors 102, 104 arereduced below about −3M and about 3M (e.g., to approximately −2.7M and2.7M), the distance y is preferably less than the distance x to provideoptimized crosstalk compensation.

Crosstalk can also be an issue between the 1-2 and 3-6 pairs.Particularly, substantial crosstalk can be generated between track T₂and track T₃. As shown at FIG. 10, a three-zone compensation arrangementis used to compensate for this crosstalk. The three-zone compensationarrangement includes a first zone of compensation Z_(B1), a second zoneof compensation Z_(B2) and a third zone of compensation Z_(B3). Thefirst zone of compensation Z_(B1) includes a capacitive coupling C7between track T₁ and track T₃, and a capacitive coupling C8 betweentrack T₂ and track T₆. The second zone of compensation Z_(B2) includes acapacitive coupling C9 between track T₁ and track T₆. The third zone ofcompensation Z_(B3) includes a capacitive coupling C10 between track T₁and track T₃. The three zones of compensation between the 1-2 and 3-6pairs can be placed at locations consistent with the vector diagramshown in FIG. 11, described above.

In general, it has been determined that varying the relativecompensation among the pairs at the primary zones of compensation foreach pair can affect alien crosstalk. Regarding the zone of compensationZ_(B1), it has been determined that varying the relative magnitudes ofthe capacitive couplings C7 and C8, such that the capacitive couplingsare non-equal, can improve overall alien crosstalk of the plug and jacksystem. In the embodiment shown, a larger capacitance is used forcapacitance C7 than C8, with the overall capacitance relating to thecapacitive coupling introduced at the plug, as described above inconjunction with FIG. 11.

In general, it has been determined that in zone of compensation Z_(B2)performance is optimized without use of a capacitive coupling betweentrack T₂ and track T₃. However, in certain embodiments, such acapacitive coupling can be included to preserve symmetry between thepairs. Likewise, in zone Z_(B3), no capacitive coupling is includedbetween track T₂ and track T₆, although in symmetric systems such acoupling could be included. Furthermore, it will be appreciated that themagnitudes of the compensation between the 3-6 and 4-5 pairs aresubstantially greater in magnitude than those between the 1-2 and 3-6pairs.

Additional crosstalk exists between the 4-5 and 7-8 pairs. In theembodiment of the crosstalk compensation arrangement shown in FIG. 10, atwo zone arrangement is used to compensate for crosstalk between thosepairs. As shown, the compensation arrangement between the 4-5 and 7-8pairs is a two zone compensation including a capacitive coupling C11 ina first zone Z_(C1) provided between track T₅ and track T₈, andcapacitive coupling C12 in a second zone Z_(C2) provided between trackT₄ and track T₈.

FIG. 12 is a schematic vector diagram showing the compensationarrangement used between the 4-5 and 7-8 pairs. As shown at FIG. 12,three crosstalk vectors are taken into consideration. The firstcrosstalk vector 110 is representative of crosstalk generated at theplug. A second vector 112 is representative of crosstalk provided at thefirst compensation zone Z_(C1). The third vector 114 is representativeof crosstalk generated at the second compensation zone Z_(C2). The firstand third vectors 110, 114 have positive polarities and magnitudes ofabout N. The second vector 112 has a negative polarity and a magnitudeabout 2N. Although the disclosed compensation arrangement is asymmetricamong the pairs, a symmetric arrangement could be provided as well.Furthermore, it will be appreciated that M (shown at FIG. 11) istypically substantially greater in magnitude than N (shown at FIG. 12).

As described above, varying the capacitive values across the 4-5 and 7-8wire pairs used in the first zone of compensation Z_(C1) can improvealien crosstalk values generated from the plug-jack system. In theembodiment shown, a completely unbalanced configuration is selected,such that Z_(C1) includes only compensation between track T₅ and trackT₈, with no corresponding balanced compensation between tracks T₄ andT₇. In further embodiments, a different, unbalanced arrangement may beselected.

In addition to the multiple zone compensation arrangements describedabove, a number of single zone compensations can also be used. Forexample, zone Z_(D1) is a single zone compensation used to compensatefor crosstalk generated between the 1-2 and 4-5 pairs, and includes acapacitive coupling C13 provided between track T₂ and track T₅. Anothersingle zone compensation Z_(E1) compensates for crosstalk generatedbetween the 3-6 and 7-8 pairs, and is provided by a capacitive couplingC14 formed between track T₃ and track T₇. Other capacitive couplings maybe included which compensate for unintended crosstalk generated withinthe board itself.

Again, each of the single zone compensations is illustrated as using anunbalanced arrangement to account for alien crosstalk generated by theplug and jack. It is observed that the “excess” alien crosstalk may becaused, at least in part, by an imbalance in connecting hardwarecontributing to excess crosstalk between the cables, particularly inshort sections of cable between connectors. Therefore, imbalancedcompensation across wire pairs can compensate for this excess crosstalk.In the embodiment shown, zone Z_(D1) includes only compensation C13between track T₂ and track T₅, but no compensation between tracks trackT₁ and track T₄. Similarly, zone Z_(E1) includes only compensation C14between track T₃ and track T₇, but no compensation between tracks trackT₆ and track T₈.

The crosstalk compensation schemes illustrated herein generally areaccomplished by first positioning a crosstalk compensation arrangementrelating to crosstalk within the plug and jack, across a variety of wirepairs. In designing the multi-zone crosstalk compensation schemes inaccordance with this disclosure, a designer will generally first locatea first zone of capacitive coupling a first time delay away from thecapacitive coupling at the plug. The designer can then position a secondcapacitive coupling, i.e. a second zone of compensation, at a secondtime delay away from the first time delay. That second zone ofcompensation can be made up of more than one capacitive coupling, andcan have capacitive couplings of differing magnitude. For example, twocapacitors can make up a zone of compensation, and can be placed atdiffering distances from a first zone. An example of such aconfiguration is illustrated by zone Z_(A2) as described above.

Once crosstalk for the plug and jack have been brought to an acceptablelevel using the techniques described above, the compensation arrangementcan be altered to improve alien crosstalk. Altering the compensationarrangement is performed to accommodate one or more zones of crosstalkcompensation having an asymmetric capacitive coupling between a wirepairs, such that alien crosstalk is reduced. This can be performed bychanging the relative magnitudes of the capacitive couplings betweenwire pairs in one or more of the zones of compensation. In certainembodiments, a designer can start with a compensation arrangement havingsymmetric capacitive couplings across complementary wire pairs (e.g.from the 3-6 pair to the 4-5 pair, having equal couplings between T₃ andT₅ and between T₄ and T₆).

The various capacitive couplings illustrated in the present disclosureprovide an example design for which far end and alien crosstalk areaddressed. Additional embodiments exist in which these types ofcrosstalk are compensated for. In the various embodiments, any amount ofasymmetry in any zone of compensation can be introduced to compensatefor alien crosstalk, from complete symmetry to complete asymmetry.

In general, the various asymmetric capacitive coupling selections madeto account for alien crosstalk are believed to, as a whole, compensatefor crosstalk generated in an overall system including both a plug and acontact set of a modular jack, as described above in FIGS. 4-7. It isparticularly notable that the crosstalk compensations selected in thepresent disclosure may not be symmetric in the sense that equalcapacitive couplings are not applied across complementary tracks of awire pair. Although this may have the effect of slightly worseperformance with respect to connector balance and crosstalk within thepair, the net effect of a number of plug and jack systems in closeproximity is an improved overall crosstalk compensation.

FIGS. 13-16 show an example circuit board layout for implementing thecompensation arrangement of FIG. 10. FIGS. 14-16 respectively show thefront, middle and back conductive layers 140, 142 and 144 of the circuitboard 132. FIG. 13 is an overlay of the three conductive layers 140, 142and 144. The circuit board 132 defines openings 301-308 thatrespectively receive posts of the contact springs CS₁-CS₈ so that thecontact springs CS₁-CS₈ are terminated to the board 132. The circuitboard also defines openings 401-408 for respectively receiving posts ofthe insulation displacement connector blades IDC₁-IDC₈ such that theinsulation displacement connector blades IDC₁-IDC₈ are terminated to thecircuit board. Vias extend through the circuit board for electricallyinterconnecting the tracks between the layers 140, 142 and 144, and tothe various capacitive couplings C1-C13. For example, vias V_(4A) andV_(4B) interconnect the portions of the track T₄ located at thedifferent layers 140, 142 and 144 to the capacitive couplings C3 and C6.Also, via V₅, interconnects the portions of the track T₅ located at thedifferent layers 140, 142 and 144 to capacitive coupling C5. Moreover,via V₆ interconnects the portions of the track T₆ located at thedifferent layers 140, 142 and 144 with capacitive coupling C6. Likewise,via V₃ interconnects the portions of the track T₃ located at thedifferent layers 140, 142 and 144 to capacitive coupling C5.

Referring to FIGS. 14-16, the capacitive coupling C1 of the first zoneof compensation Z_(A1) is provided by opposing capacitor plates C1 ₅ andC1 ₃ respectively provided at layers 142 and 144. The capacitivecoupling C2 of the first zone of compensation Z_(A1) is provided byopposing capacitor plates C2 ₄ and C2 ₆ that are respectively providedat the layers 142 and 144. The capacitive coupling C3 of the secondcompensation zone Z_(A2) is provided by opposing capacitor plates C3 ₄and C3 ₃ that are respectively provided at layers 142 and 144. Thecapacitive coupling C4 of the second compensation zone Z_(A2) isprovided by opposing capacitor plates C4 ₆ and C4 ₅ that arerespectively provided at layers 142 and 144. The capacitive coupling C5of the third compensation zone Z is provided by a capacitor plate C5_(5A) that is provided at layer 142. The capacitive coupling C5 is alsoprovided by inter-digitated capacitor fingers C5 _(5B) and C5 _(3B) thatare provided at layer 140. The capacitive coupling C6 of the secondcompensation zone Z_(A3) is provided by capacitor plate C6 _(6A)provided at layer 142. The capacitive coupling C6 is also provided byinter-digitated capacitor fingers C6 _(6B) and C6 _(4B) provided atlayer 140.

The capacitive coupling C7 of the first compensation zone Z_(B1) isprovided by opposing capacitor plates C7 ₁ and C7 ₃ that arerespectively provided at layers 142 and 144 of the circuit board. Thecapacitive coupling C8 of the first compensation zone Z_(B1) is providedby opposing capacitor plates C8 ₂ and C8 ₆ that are respectivelyprovided at the layers 142 and 144 of the circuit board. The capacitivecoupling C9 of the second zone of compensation Z_(B2) is provided byopposing capacitor plates C9 ₁ and C9 ₆ that are respectively providedat layer 142 and 144 of the circuit board. The capacitive coupling C10of the third zone of compensation Z_(B3) is provided by opposingcapacitor plates C10 ₁ and C10 ₃ that are respectively provided atlayers 142 and 144 of the circuit board.

The capacitive coupling C11 of the first compensation zone Z_(C1) isprovided by opposing capacitor plates C11 ₅ and C11 ₈ that arerespectively provided at layers 142 and 144 of the circuit board. Thecapacitive coupling C12 of the second compensation zone ZC2 is providedby adjacent leads C124 and C128, respectively, located at layer 142. Thecapacitive coupling C13 of the zone of compensation Z_(D1) is providedby opposing capacitor plates C13 ₂ and C13 ₅ provided at layers 142 and144 of the circuit board. The capacitive coupling C 14 of the zone ofcompensation Z_(E1) is provided by opposing capacitor plates C14 ₇ andC14 ₃ respectively provided at layers 142 and 144 of the circuit board.

Various manufacturing and routing techniques may be implemented in theplacement of the tracks, vias, and capacitors described herein.Additional details regarding the routing and placement of circuitcomponents are described in U.S. patent application Ser. No. 11/402,544,filed Apr. 11, 2006, which was previously incorporated by reference inits entirety.

The above specification, examples and data provide a completedescription of the manufacture and use of the composition of theinvention. Since many embodiments of the invention can be made withoutdeparting from the spirit and scope of the invention, the inventionresides in the claims hereinafter appended.

1. A method for providing crosstalk compensation in a jack, thecrosstalk compensation being adapted to compensate for undesiredcrosstalk generated at a capacitive coupling located at a plug insertedwithin the jack, the method comprising: positioning a first capacitivecoupling a first time delay away from the capacitive coupling of theplug, the first capacitive coupling having a greater magnitude and anopposite polarity as compared to the capacitive coupling of the plug;positioning a second capacitive coupling at a second time delay from thefirst capacitive coupling, the second time delay corresponding to anaverage time delay that optimizes near end crosstalk, the secondcapacitive coupling having generally the same overall magnitude but anopposite polarity as compared to the first capacitive coupling, andincluding two capacitive elements spaced at different time delays fromthe first capacitive coupling.
 2. The method of claim 1, furthercomprising providing a third capacitive coupling positioned a third timedelay away from the second capacitive coupling, such that the third timedelay is approximately the same as the first time delay.
 3. The methodof claim 1, wherein the two capacitive elements connect between wires ofa first wire pair and a second wire pair.
 4. The method of claim 3,wherein the two capacitive elements connect between different wires ofthe first wire pair and the second wire pair.
 5. The method of claim 1,wherein different time delays of the two capacitive elements in thesecond capacitive coupling are centered about the average time delay. 6.The method of claim 1, wherein the first capacitive coupling existsacross different wire pairs than the second capacitive coupling.
 7. Atelecommunications jack for use in a twisted pair system, the jackcomprising: a housing defining a port for receiving a plug; a pluralityof contact springs adapted to make electrical contact with the plug whenthe plug is inserted into the port of the housing; a plurality of wiretermination contacts for terminating wires to the jack; a circuit boardincluding conductive tracks that electrically connect the contactsprings to the wire termination contacts; and a crosstalk compensationarrangement that provides crosstalk compensation between selected tracksof the circuit board, the crosstalk compensation arrangement including afirst zone of compensation a first time delay away from the capacitivecoupling of the plug and a second zone of compensation at an second timedelay from the first zone of compensation, the second zone ofcompensation including two capacitive elements spaced at different timedelays from the first zone of compensation to optimize far end crosstalkand having an average time delay that optimizes near end crosstalk. 8.The telecommunications jack of claim 7, wherein the crosstalkcompensation arrangement further includes a third zone of compensationthat is positioned a third time delay away from the second zone ofcompensation, the first and third time delays being generally equal toone another.
 9. The telecommunications jack of claim 7, wherein thefirst zone of compensation has a greater magnitude and an oppositepolarity as compared to the capacitive coupling of the plug, and thesecond zone of compensation has generally the same overall magnitude butan opposite polarity as compared to the first zone of compensation. 10.The telecommunications jack of claim 7, wherein the second zone ofcompensation is positioned such that the second time delay is greaterthan the first time delay.
 11. The telecommunications jack of claim 7,wherein the second zone of compensation is positioned such that thesecond time delay is less than the first time delay.
 12. A crosstalkcompensation system within a telecommunications jack, the systemcomprising: a circuit board; a plurality of contact springs mounted onthe circuit board, the contact springs including first, second, third,fourth, fifth, sixth, seventh and eighth consecutively arranged contactsprings; a plurality of wire termination contacts mounted on the circuitboard, the wire termination contents including first, second, third,fourth, fifth, sixth, seventh and eighth wire termination contacts forterminating wires to the jack; a plurality of tracks on the circuitboard, the tracks including first, second, third, fourth, fifth, sixth,seventh and eighth tracks that respectively electrically connect thefirst, second, third, fourth, fifth, sixth, seventh and eighth contactsprings to the first, second, third, fourth, fifth, sixth, seventh andeighth wire termination contacts; a crosstalk compensation arrangementthat provides crosstalk compensation between the tracks of the circuitboard, the crosstalk compensation arrangement including a first zone ofcompensation a first time delay away from the contact springs and asecond zone of compensation at an second time delay from the first zoneof compensation, the second zone of compensation including twocapacitive elements spaced at different time delays from the firstcapacitive coupling and having an average time delay that that optimizesnear end crosstalk.
 13. The system of claim 12, wherein the second zoneof compensation includes a capacitive element connected between thethird track and the fourth track.
 14. The system of claim 13, whereinthe second zone of compensation includes a second capacitive elementconnected between the fifth track and the sixth track.
 15. The system ofclaim 14, wherein the capacitive element is placed at a time delayfurther away from the first zone of compensation than the secondcapacitive element.
 16. The system of claim 12, wherein the first zoneof compensation includes a capacitive element connected between thethird track and the fifth track.
 17. The system of claim 12, wherein thefirst zone of compensation includes a capacitive element connectedbetween the fourth track and the sixth track.
 18. The system of claim12, wherein the crosstalk compensation arrangement includes a third zoneof compensation that is positioned a third time delay away from thesecond zone of compensation, the first and third time delays beinggenerally equal to one another.
 19. A method for determining thepositions of first and second zones of crosstalk compensation in a jack,the first and second zones of crosstalk compensation being adapted tocompensate for undesired crosstalk caused by an undesired capacitivecoupling located at a plug inserted within the jack, the first zone ofcrosstalk compensation including a first capacitive coupling positioneda first time delay away from the undesired capacitive coupling of theplug, the first capacitive coupling having a greater magnitude and anopposite polarity as compared to the undesired capacitive coupling ofthe plug, the second zone of crosstalk compensation including a secondcapacitive coupling having two capacitive elements positioned, onaverage, a second time delay away from the first capacitive coupling,the second capacitive coupling having generally the same magnitude butan opposite polarity as compared to the first capacitive coupling, themethod comprising: positioning the first and second capacitive couplingsin initial positions in which the first and second time delays aregenerally equal to one another; adjusting the position of the secondcapacitive coupling from the initial position to an adjusted position toprovide improved near end crosstalk compensation; adjusting the positionof the first and second capacitive elements to different lengths toprovide improved far end crosstalk compensation while maintaining theadjusted position of the second capacitive coupling as the averageposition of the first and second capacitive elements.
 20. The method ofclaim 19, further comprising positioning a third zone of compensation athird time delay away from the second zone of compensation, the firstand third time delays being generally equal to one another.
 21. A methodof designing a crosstalk compensation system for a telecommunicationsjack, the method comprising: positioning a first zone of crosstalkcompensation across at least a first wire pair and a second wire pair ona circuit board within a telecommunications jack, the first zone ofcrosstalk compensation placed at a first distance from contact springsassociated with the first wire pair and the second wire pair;positioning a second zone of crosstalk compensation across the at leastfirst and second wire pairs at a second distance from the first zone ofcrosstalk compensation, the second zone of crosstalk compensationincluding a first capacitive coupling and a second capacitive coupling;altering the position of the capacitive couplings to establish adistance between the first capacitive coupling and the second capacitivecoupling while maintaining the second distance as an average distancefrom the first zone of crosstalk compensation; wherein altering theposition of the capacitive couplings provides improved far end crosstalkcompensation.
 22. The method of claim 21, wherein the first and secondcapacitive couplings connect between different wires of the first wirepair and the second wire pair.